The present invention provides a testing device and a method of its use, in particular for distinguishing between hydrocarbons.
There are many occasions when liquids are to be mixed commercially on a large scale and/or frequently, in particular distillate liquid products in a refinery or derived from a refinery, and it is essential that the correct liquids are mixed. Examples of such mixing occurs during transfer of fresh product e.g. gasolines or kerosenes to replenish tanks containing previously made product, as well as the dispensing of propulsion fuel e.g. motor gasoline or aviation gasoline, marine fuels, jet fuel or diesel into tanks of appropriate vehicles e.g. cars, lorries or piston or jet aircraft. The consequences of mis-fuelling are at best a nuisance and at worst lethal in the case of aircraft. In particular it is essential to be able to distinguish easily between aviation gasoline and jet fuel, or between motor gasoline and diesel. Existing methods involve use of a number of different techniques e.g. different colours and labels, audible warnings, and different nozzle sizes.
A device and method have now been found to achieve the distinction quickly, easily and routinely.
The present invention provides a method for controlling the movement of a liquid preferably comprising a liquid hydrocarbon from a first location to a second location, via closure means capable reversibly of moving at least partly (and preferably completely) between an open and a closed position, at least one of said first and second locations having a vapour space, and preferably at least one of the first and second locations having a vapour space above the liquid, which process comprises analyzing the vapour in one or both locations, comparing the results of the analysis(es) with a standard or each other, and using the results of the comparison to control the movement of the closure means. Preferably the first location has vapour space above the liquid and the second location has vapour space, optionally above a liquid, and the process especially comprises analyzing the vapour in or from the second location and optionally in or from the first location comparing the results of the analysis in or from the second location, with a standard or the results from the analysis in or from the first location.
The invention also provides an apparatus for controllable passage of a liquid which comprises a first zone containing said liquid, a reversible closure means, a first line between said first zone and said closure means, a second zone defining a vapour space for vapour of said liquid and optionally also said liquid, a second line from said closure means to or into said second zone, at least one detector for analyzing vapour in or from said second zone and/or above liquid in said first or second zones, means for transmitting the data from said detector(s) to processing means for comparing said data from one of said zones with a pre-set level or with data from the other of said zones, means for controlling movement of enclosure means, operation of said processing means and said controlling means being dependant on said comparison.
The present invention also provides a modification of said apparatus in which said second line passes into said second zone but is not integral with it and said detector is inside or preferably outside said second line and analyzes the vapour from said second zone. In this case the second line preferably has mounted on or in it said detector, and may be reversibly inserted into said second zone and the vapour analyzed. The second line provides the line for transporting the liquid as well as a support for the detector.
The present invention also provides an apparatus for dispensing a liquid e.g. a hydrocarbon such as a fuel which comprises a nozzle for inserting into a tank containing vapour e.g. a fuel tank, a reversible closure means preferably valve in said nozzle or in a feed line thereto for control of dispensing of liquid e.g. fuel, a detector for contacting the vapour from or in the tank, e.g. for insertion into said vapour, said detector being preferably capable of being in vapour contact with the dispensing end of said nozzle, means for passing a signal from said detector to a processing means for comparison of said signal, and a controller receiving output from said comparison for controlling movement of the liquid e.g. fuel, e.g. allowing or stopping its movement, preferably using said valve.
The invention will be described with respect to differentiating between fuels, but is applicable to other liquids as described below.
The movement of the liquid from the first zone to the second may be from a tank, a bulk one such as a non movable one e.g. an underground fuel tank via a fuel dispenser e.g. nozzle or bowser into a tank of a movable vehicle e.g. one powered by a combustion engine, as at a gasoline or rail car filling station, or an aircraft or boat, ship or tanker refuelling point or cargo loading point. The first zone may also be in a tank or pipe and the second zone a tank, e.g. for passing fresh gasoline feed components or blended gasoline to fill a partly full tank of previously made material, for example in a tank farm or from a fuel tanker into the pipes and tank of a filling station or from a tank on land and pipes into a ship tank. The first zone may also be in a tank and the second in a pipe, leading elsewhere in a refinery e.g. moving gasoline from a tank to a second location for subsequent blending. The first and second zones may also be in refinery pipes. In the case of pipes, there may be head space above the liquid level in which vapour is present and can be analyzed. The tanks are usually storage vessels for the liquid, either stationary as in underground or above ground repositories for fuel, especially ones periodically filled with fuel, e.g. from sea, rail or road tankers or fed directly by pipeline e.g. in/or from a refinery, or moveable in transport vehicles for propelling them e.g. in cars, lorries or boats or for containing them e.g. in gasoline road rail or sea tankers. Thus the tanks may be storage vessels or containers for long or short term retention of fuel.
The liquid being moved into the second location is one whose vapour is different from that of a liquid which it is not desired to be present in the second location e.g. because they are incompatible with each other or more usually because of the unsuitability of the undesired liquid in that second location. An Example of the latter is when the second location is a fuel tank for powering a combustion engine, for which one or more liquid fuels cannot or should not be used.
The liquid being moved preferably comprises a hydrocarbon which is liquid at 25xc2x0 C. e.g. fuel, lubricant or crude oil containing partly volatile hydrocarbons, e.g. of 4-20 such as 4-10 carbons and usually aliphatic or aromatic, and possibly also non-hydrocarbon components, such as oxygen compounds e.g. ether octane boosters or phenols, or antioxidants, nitrogen compounds such as inhibitors/dispersants or cetane improvers such as organo nitrates and/or sulphur compounds e.g. impurities in the fuel, and/or perfumes and/or octane boosters e.g. organo leads.
The apparatus and method can also be used to distinguish between hydrocarbon liquids e.g. different types of crude oils, different kinds of gasolines e.g. leaded/unleaded or super unleaded fuels (with non lead octane boosters) or oxygenated/non oxygenated fuels, e.g. ones containing oxygen such as ethers e.g. MTBE, ETBE or TAME or alcohols, or feedstocks therefor e.g. reformate, alkylate etc. middle distillate fuels e.g. kerosene, diesel and fuel oils or bunker fuels such as marine fuel, heating and electricity generating oils. Other examples are the distinction between high sulphur diesel oil (e.g. a residual fuel) and low sulphur diesel oil e.g. a middle distillate, the diesel oils containing more or less than 0.05% of sulphur containing compounds (expressed by weight as sulphur). Diesels of nominally the same grade e.g. cetane number but containing different compounds may be differentiated. Further examples involve distinction between gasoline, e.g. motor gasoline, paraffin (or gas oil) diesel and heating oil, e.g. in an agricultural environment; the order from gasoline to heating oil is the order of decreasing volatility. Distinction between hydrocarbon fuels e.g. diesel and biofuels e.g. esters of long chain acids e.g. rape seed oil can also be made. Other examples in the petroleum industry are diffentiating between lube oils e.g. synthetic and by hydrocarbon oils, and between heat transfer oils. Further examples of liquids are different types of solvents or reactants used in chemical, petrochemical or pharmaceutical industries.
The liquid to be moved may be liquid at 25xc2x0 C., either under atmospheric pressure, or under higher pressures e.g. a liquefied gas, such as liquid petroleum gas (LPG, predominantly butanes) and compressed natural gas (CNG, predominantly methane). Preferably liquefied gases are moved at reduced temperature e.g. xe2x88x92200xc2x0 C. to 0xc2x0 C. such as when the invention is used to distinguish between liquid nitrogen, liquid oxygen and/or liquid air, or between LPG and SNG. The liquid to be moved may be under a pressure less than atmospheric in order to increase its volatility and hence the sensitivity of the sensors. The liquid being moved may be at raised temperature e.g. 50-200xc2x0 C., in order to decrease the viscosity or because its melting point is above 25xc2x0 C., examples of this use are between bitumens or between petroleum waxes or other materials solid at 25xc2x0 C. but distinguishable from their vapours.
The invention may be aimed at ensuring that the vapour over the first zone is the same as in the second zone i.e. that the liquid passed into the second zone is the same as that previously present in the second zone. It is therefore important that the liquid does not flow, e.g. closure means remains closed, if the vapours are different or if the vapour in the second zone does not otherwise meet a particular standard or threshold. It is particularly important to stop the mixing of a liquid from the first zone with vapours of a different liquid in the second zone when the initial boiling points of the liquids under atmospheric pressure differ by more than 100xc2x0 C. especially more than 135xc2x0 C., in particular when one of the 2 liquids is aviation gasoline, e.g. comprising isopentane or butane with iso octanes, and/or aromatics such as toluene, and the other is jet fuel comprising kerosene, or alternatively when one of the liquids is motor gasoline or a component thereof and the other is a diesel/gas oil/vacuum gas oil/fuel or bunker oil fraction. The invention is of particular value to enable distinction to be made between gasolines, and hydrocarbons with initial atmospheric boiling points of at least 140xc2x0 C. especially at least 170xc2x0 C., or hydrocarbons having a boiling point of at least 250xc2x0 C.
The movement is stopped by the closure means, which may be a valve, in which case any movement is otherwise impelled or propelled by gravity or a pump, or the closure means may itself comprise the pump, acting as valve and pump.
Alternatively the movement may be allowed by operation of closure means for liquid moving in a different line from a line between the first location and second location as with a flow diverter or closure of a valve in a recirculating liquid stream forcing the liquid to flow via a different route i.e. between the 2 locations. The movement may be stopped by the presence of an unopen closure means which has fail safe arrangement such that it cannot be opened at all unless another criterion is met e.g. an engine running to pull vacuum on the closure means allowing it to open if required as in a vacuum lock. The closure means e.g. valve may be in or near to the liquid dispenser e.g. the nozzle as is preferred, or upstream thereof and in contact therewith (e.g. in a separate housing from the dispenser); the closure means may also be in or near the dispensing pump. The separate housing may also comprise processing means second signal passage means, controlling means and a second valve controlling movement of said liquid. Preferably the controlling means is activated before any liquid is passed, rather than allowing a small amount of liquid to pass before the controller checks it is the xe2x80x9ccorrectxe2x80x9d liquid. The control decision may be passed to the closure means to open or shut a valve or operate a relay or a pump, by pneumatic means or electromagnetic radiation e.g. radio, light, laser means, such as use of light down optical fibres. Preferably the closure means stops liquid flowing, unless it receives the xe2x80x9ccorrectxe2x80x9d instruction to open, rather than the reverse. If desired a decision that the liquid to be passed from the first to the second zone is the xe2x80x9cwrongxe2x80x9d liquid and therefore is stopped from flowing may activate an alarm e.g. an audible and/or optical waning.
The detector for analysing may be in a vapour space above a tank, or in an entry neck thereto or, in the case of a line, in its top or better in a small extension over the line with head space. If desired a sampling point may be present over a liquid line, into which sample zone a portion of liquid may be drawn (and hence vapour produced). The latter may be useful for safety purposes especially to seal off the sample and detector zone from the line.
In the analysis, the nature or total concentration of one or more vapour components may be obtained or both the concentration and nature of the vapour components may be found. The output signal from the analyzer is passed to the processor e.g. a mini computer usually by wire or radiation to process the data and instruct the valve what action if any to take. In relation to the former approach the total concentration may be obtained as a single signal e.g. from the second zone, and this may be compared either to a fixed reference point or a standard concentration or to the corresponding value for the vapour in the first zone. In the comparisons, compensation means may be included e.g. in the controller to correct for differences between the temperature of measurement e.g. in the second zone and the fixed reference point or standard or first zone. Thus at a temperature of measurement of 35xc2x0 C., avgas vapour concentration for example would be high but so would the kerosene vapour concentration so compensation for this is usually desirable. A comparison may be made so that action is taken to open the valve/operate the pump when the signal is above a level of background noise, or above any chosen level e.g. 10% above base, or part way e.g. 25-75% between the level for the fuel in the first zone e.g. gasoline and that for a fuel which should not be present in the second zone e.g. diesel; thus a signal above say 50% between the levels would allow the gasoline to move while one less than 25% would stop the movement as it would show the presence of diesel in the second zone. Alternatively if diesel were in the first zone, signal from the second zone above the desired level e.g. due to gasoline would stop movement of the diesel. In a similar way if the amplitude of the signal from the first zone were within given tolerances the same as that from the second zone, the liquid could pass, but not otherwise.
The key when considering analysis for the total concentration of one or more vapour components is that the signal from the second zone should be above or below a threshold value in order to allow liquid to move, being above the threshold when the amplitude of the signal from the second zone for the desired liquid is above that of the non desired liquid, and below the threshold in the reverse case.
The invention is particularly applicable when frequent connections are made in dispensing of liquids, in particular when the dispensing can be from one of a number of tanks of different liquids, into a number of different second locations; an example of this is the feeding from a multicompartment tanker e.g. (road, rail or boat tanker) into a number of separate tanks e.g. at a filling station or the feeding from one or a number of different tanks into a number of different tanks e.g. of vehicles.
The analysis may be by nature of one or more of the components in the liquid to help distinguish more finely between liquids. In this case the detector (or detectors) provide more than 1 signal, which can provide a finger print or pattern characteristic of the liquid and special computer techniques e.g. chemometric analysis such as regression techniques e.g. Principal Component Analysis or Cluster Analysis or Neural network analysis can be used to compare the liquids. Again similar analysis within tolerances to standards or above fixed levels or comparison with other liquids would allow passage of the liquid. Preferably, however, only the total concentration of vapour is measured for ease of operation and simplicity. Thus when the analysis is of total vapour concentration or is specific to at least one compound present in said liquid, the comparison of the results of the analysis controls movement of the closure means depending on whether the total vapour concentration or the amount of said compound(s) present respectively is above or below a defined level.
The output from the processor is usually a go signal to instruct the controller to open the valve or allow it to open or activate the pump, or no signal or a no go signal to close the valve or not allow it to open. Once the signal has been passed any subsequent change in the concentration of vapour usually does not trigger a fresh signal. So a high concentration of vapour can trip a go signal but a subsequent reduction usually does not trip a no go signal; by this means once the vapour in the second zone has been xe2x80x9crecognizedxe2x80x9d as correct, the flow of the liquid can be governed by any manually or remote operated valve without risk of the detector signal overriding it. The controller usually acts almost instantly e.g. whenever the sensor shows the xe2x80x9ccorrectxe2x80x9d liquid, but may have an in-built delay, which may be useful e.g. when scheduling blending operations for a refinery tank farm moving components to or from a tank. In this latter case the controller usually has a memory, a memorized reading from the sensor for comparison with a preset level and a go/no-go logic. The closure means activatable by the controller may be upstream of the pump i.e. between tank and pump, as may be the case with a number of tanks separately feeding a single pump, but is preferably at or in proximity of the fuel dispenser. In the latter case the closure means may be separate from the dispenser and upstream, e.g. in the form of a separate fitting retro fittable between the dispenser and its feed line from the pump. The valve may otherwise be part of the dispenser (see below), or downstream of the dispenser e.g. in a sheath retrofittable with the entrance to the receiving tank, of a vehicle such as an aeroplane, car or boat (see below).
The benefit of the method is that it stops mis-fueling or mixing between liquids, usually of widely different boiling point and hence concentration of vapours therefrom. The control can be on line or at line.
In an embodiment of the method of the invention, the first location may have a vapour space optionally above the liquid, and there is a vapour space at the second location, which may or may not also be above a liquid and may or may not contain vapour. The vapour at the first location can be analyzed and compared to a standard, the standard being for the liquid desired to be moved to the second location; an example of this is the filling of empty clean tanks with a specified fuel from a store. The standard may have been preset or relate to the last vapour at the second location (e.g. with a time delay). The vapour at the second location can also be analyzed and compared to the standard, there being no vapour above liquid at the first location.
The overall apparatus can be integral with no relative movement of the parts apart from any movement of the closure means or movement due to use of flexible lines; an example of this is the transfer of fuel in integral lines from a first line or tank to another line or tank. The apparatus may also be non integral e.g. with relative movement of the second line and second zone. These may be releasably joined e.g. with clips, as in the case of dispensers for diesel or fuel oil temporarily joined to input lines for tanks on land, or in vehicles or on ships or for aviation fuels temporarily joined to input lines in aircraft. The second line and second zone may also not be joined, but moved in and out thereof. This is the case with a fuel nozzle removed from a holder e.g. in a fuel xe2x80x9cpumpxe2x80x9d stand in a filling station and inserted into a fuel tank of a vehicle. The nozzle can carry the detector into the second zone.
The detector can also be mounted in or especially on an extra tube which can be temporarily joined to the nozzle e.g. as a sheath surrounding the nozzle end, which may be locked in place, or by a clip on the extra tube onto a corresponding flange on the nozzle or the reverse. The extra tube has in it a valve movable between open and shut position on instruction from a controller. The extra tube may also not be joined to the nozzle but may be separate from the tank but capable of being carried with the tank, or may be releasably or non releasably attached to the tank e.g. in its neck. The extra tube may be adapted to surround or be surrounded by any sieve present in the nozzle or entry to the tank, e.g. outside a frustoconical sieve, the valve being a flap in the bottom of the extra tube. In this way the detector may be associated with the tank providing the second location and hence be carried by the vehicle/aircraft/boat etc i.e. with the second zone, in which case the processor and controller may be similarly carried. A negative signal from the processor would ensure the valve remained shut. By this means, the vehicle/boat/plane etc carries with it all the equipment needed to stop entry of the xe2x80x9cwrongxe2x80x9d liquid, without having to rely on equipment in association with the fuel source i.e. the tank on land or in the filling or refuelling station. Such arrangements with the extra tube are easy to retrofit to existing systems.
If desired the extra tube may have a number of detectors each capable alternately of being brought into contact with the vapour, with means, e.g. externally mounted on the tube, of bringing each detector in line. Thus a rotatable disc externally carrying identification of each of the various vapours to which each detector is sensitive may be used to allow the vapour of the desired fuel feed to contact the appropriate detector. Thus dialing the appropriate fuel on the disc on the extra tube would give the user freedom to allow that fuel to fill the tank. This approach would be valuable where the nature of the fuel in the dispensing tank is unknown or not known with certainly, or one dispensing device is fed by more than one dispensing tank.
The apparatus may comprise a line passing from a first to a second location which are separated by a reversible closure means e.g. valve. A pump separate from the valve may be present in said line or upstream of the first location. The detector may be in the vapour space over the first or preferably the second zone or especially temporarily in the second zone i.e. near the end of the line inserted into said zone. The detector provides a signal(s) to the processor which passes a signal to a controller which activates the valve/pump. The signals may be sent by wire or fibre optics or by electromagnetic radiation, especially infra red, microwave or other radio waves. Advantageously where the fuel dispenser comprises a nozzle and fuel control valve, as well as a detector, the detector can pass the signal to a processor also comprised by the dispenser by wire or fibre optics or radiation, and hence to a controller for activating the valve. When the controller and pump or valve, or processor and controller are separated by a fuel conducting line, passage of a signal between them may be by wire line but is preferably by fibre optic line or electromagnetic radiation.
When the detector is only to be temporarily inserted into the second zone, the detector may be inside the second line, but preferably is outside the line but mounted on it, so it can detect the vapour of the second zone separately from any residual vapour from the second line. In this case the apparatus can comprise the second line comprising the nozzle with analyzer, together with a control valve activated from the analyzer results, a pump for pumping the liquid and a second valve e.g. manually operated for dispensing the fuel; the line from pump to the nozzle can be rigid or flexible or articulated.
The present invention also provides a fuel dispenser which comprises a nozzle for exit of the liquid e.g. fuel, a conduit through the dispenser for the liquid e.g. fuel, a valve in said conduit urged to a closed position by urging means but releasably openable against said urging means, a manually operatable actuator to open said valve, a vapour detector comprised by said dispenser adapted to be in vapour contact with vapours at the exit end of said nozzle, means for passing the output from said detector to a data processor and means for controlling said valve from the output of said processor. In this form the dispenser itself has the control means capable of stopping flow of xe2x80x9cincorrectxe2x80x9d fuel rather than the control means being separate from the dispenser e.g. with the pump in the fuel stand in the filling station which would need also means for passing the signal output from the controller to the valve/pump back to stop the flow, e.g. along a wire associated with the line for fuel from pump to dispenser.
When the detector is not itself in or moved into the second zone, it is preferred to withdraw the vapour from the second zone to the detector. Thus especially in connection with movement of liquid from a non movable tank to a tank of a movable vehicle, the vapour in the second location is analyzed by withdrawing it past a detector associated with a dispenser for the liquid comprising a releasable valve, said dispenser being in a liquid line between the first and second location. The dispenser preferably has a nozzle, an internal liquid conduit a valve and a body portion and the detector is located in or on the nozzle, between the nozzle and body portion or in the body portion.
The dispenser usually has the detector in a protective housing, which in the case when the detector is inside the nozzle, may be open towards the outer dispensing end of the nozzle, and in the case of the detector inside the nozzle, the housing is preferably not open towards the inside of the nozzle. By this means the detector has reduced contact with liquid fuel rather than fuel vapour. Preferably the dispenser incorporates means for purging the detector of vapour after use e.g. by use of air or an inert gas after the dispensing of fuel has ceased and/or a liquid level detector to shut off flow of fuel when the level in the tank is sufficiently high or frothing occurs at the tank entrance. Such a liquid level detector may comprise a hollow narrow tube inside the nozzle separate from the fuel and extending from the dispensing end of the nozzle to its head end, where a conduit leads from that tube to a safety anti-tilt device causing fuel flow cut out, if the nozzle is on its side e.g. on the floor. This device may be a ball which moves in a restricted space between a location allowing free movement of vapour in the conduit to a location where the movement is stopped because the ball blocks an exit hole for vapour. The liquid detector has an automatic cut out releasing the valve to its closed position in the event of decreased air pressure in the hollow tube and conduit from the rise in liquid level due to overfilling or frothing. The vapour detector may be located inside the above narrow tube, or preferably in the housing of the safety device or automatic cut out. The signal leads from the vapour detector may pass to a processor and controller also in the dispenser e.g. in the housing, or may return to the pump fuel stand; preferably the signals are sent by electromagnetic radiation but may be sent via wires or optical fibres, which may extend longitudinally in or on the walls of the fuel line between dispenser and pump. The automatic cut out means usually comprises the narrow tube to the nozzle, the conduit, which often contains the anti tilt device, an enclosed chamber with an internally spring loaded diaphragm constituting one wall, the chamber operating into a further thin passage extending longitudinally in the dispenser, separate from the fuel, the passage leading to a fine tube ending in the throat of the valve seat, against which the dispenser valve is urged in its closed position. The cut out means operates by passage of the fuel through the throat on depression of the dispensing handle causing by a Venturi effect a reduced pressure in the fine tube which causes suction all the way through to the narrow tube in the nozzle; if the latter tube is open, the pressure drop in the line is small and air is freely drawn through from the narrow tube to the fine tube and into the throat. If the narrow tube is blocked e.g. by liquid in the case of frothing, the pressure is rapidly reduced causing the diaphragm to more inwards into the chamber. The movement causes movement of an external blocking pin or rods to which the diaphragm is externally attached, the pin or rods restraining movement of the dispenser valve back to its valve seat. Thus the sensor can be used to block the mechanism of the automatic cut out, resulting in cut out and valve closure. Thus the operation of the automatic cut out draws the vapour from nozzle end to the detector in the line of the cut out mechanism.
The sensor or processor may send the signal to the processor or controller respectively and hence the pump to activate or stop the pump, or engage/disengage a locking device on the manually operatable activator e.g. dispenser trigger or may send a signal to activate the valve in the dispenser itself. In the last case, the dispenser may, as described above, have already an automatic cut out, which is usually in the form of a pressure activated diaphragm or similar device, which on activation results in release of a spring resulting in closure of the valve. The sensor may send the signal to a processor controlling the activation of the diaphragm; thus the sensor signal may activate an induction coil causing a ball or rod e.g. in an anti tilt device to move and hence move the diaphragm. Alternatively the processor may activate a pump to open a sensor valve in the hollow liquid level detector tube. In this case the sensor may check the vapours from the tank and, if acceptable for the fuel to be fed through the valve and dispenser (e.g. both are jet fuel), then the sensor valve may open, allowing the manual operation of the dispenser in the usual way; if the sensor finds the wrong fuel in the tank compared to the input feed lines, then this sensor valve remains closed, thereby causing the automatic cut out to operate i.e. via the diaphragm to keep the dispenser operation blocked. In a third operation the processor noting a signal for the wrong fuel may cause creation of a pressure difference e.g. in the hollow liquid level detector tube, thereby activating the cut out, and hence not allowing fuel flow; the pressure difference may be created by activation of a pump or other movement of air or operation of a flap or mini valve in the detector tube.
With some dispensers, the automatic cut out may not be needed for safety reasons, but a cut out mechanism comprising the hollow tube, housing for the cut out and diaphragm and associated springs etc. may be used instead for the analysis, location of sensor, and control of the invention. Hence, the hollow tube may lead to the housing, where the sensor is located, as well as or instead of the diaphragm. The activation by the sensor may result in movement of the diaphragm, overriding the manual operation of the flow valve. The diaphragm (and hence the valve) may be released by the safety device, automatic cut out and/or vapour detector.
In this latter embodiment of the dispenser the detector may be in a head portion of the dispenser e.g. in association with the diaphragm, such as to override and trip it. Advantageously however the detector is in a position in relation to the narrow liquid level detector tube upstream of the head portion of the dispenser, which comprises the valve and diaphragm. In this case the nozzle and head portion of the dispenser may be separated by a hollow boss or collar or annular chamber having a core for passage of the fuel and optionally a separate hollow tube or channel adapted to be located in relation to corresponding tubes or channels in the nozzle and in the head end. The boss, collar or chamber also comprises a detector e.g. one located in an enclosed chamber therein open to the tube or channel, as well as a processor taking a signal from and analyzing the results from the detector and for activating means to stop passage of the vapour in the tube of channel to the automatic cut out, e.g. a controller to act on instructions from the processor. In this way the detector and processor and stopping means may be in an annulus in the boss, chamber or collar, which is separate from but in use engageable with the nozzle and head portion. Such an approach makes easy retrofitting of the detector, processor and stopping means to an existing nozzle and head portion with automatic cut out. Usually if the dispenser has an automatic cut out the sensor will activate the cut out when the incorrect fuel is detected, but when the dispenser is not so fitted, then it usually will pass a signal by radiation electrical wire or fibre optics to the pump housing to stop passage of fuel.
The collar or chamber in the dispenser may be annular or toroidal in shape, and may optionally be reflective inside e.g. coated with reflective metal e.g. silver. The vapour passes into the chamber. Through it may be directed analyzing radiation from a source, going round the annulus and to a detector located upstream of the entry of the radiation, to give the radiation a long and relatively constant path length. The collar or annular chamber may have a perforated wall e.g. the outward facing end or diameter thereof; the vapour may then enter through a circumferential surface or an inward facing diameter pass through the device past the sensor and pass outside through the perforated face. A mechanical piston, activated directly or indirectly by movement of the nozzle into the tank, may effect aspiration of the vapour through the chamber, particularly when no automatic cut device is provided.
The dispenser may also comprise a sheath or bellows at least partly longitudinally surrounding the dispenser e.g. surrounding the nozzle down to its dispensing end; there may also be a means for sucking vapour past the handle end of the nozzle which means may be comprised by the dispenser or be distant therefrom e.g. back at the pump and connected to the dispenser by a line part of or attached to the fuel hose line. Such sheaths or bellows are used in vapour recovery systems. In this case the detector may be present between the sheath/bellows and the nozzle, e.g. mounted towards the handle end of the nozzle, rather than the dispensing end. The vapours from the second zone are thus withdrawn past the nozzle and analyzed there, rather than analyzed in the zone. Thus the sheath or bellows e.g. of flexible plastics material may be collapsible in the manner of a concertina about the nozzle but be close fitted to the dispenser body near the manual actuator on the lower side of the dispenser, and with a rigid walled channel on the upper side of the dispenser, the channel leading e.g. to suction means for vapour recovery. In the channel the sensor may be located to be acted upon by the vapour. The sheath or bellows may have a toroidal end with rigid material to reinforce it and/or weigh it down e.g. a ring or sections thereof of rigid plastic or plastic covered metal, and the sheath may be separated from the nozzle by one or more separators loosely surrounding the nozzle. In this way insertion of the nozzle into the tank collapses the sheath or bellows but allows an adequate seal to the body surrounding the tank e.g. the side of the vehicle. Alternatively the sheath or bellows may lead to a sensor within the annulus surrounding the nozzle, but not mounted on the upper side of the body of the dispenser. In this embodiment the sheath or bellows is a pendant skirt surrounding the nozzle and ending in the weighted or reinforced end. Above the collapsible skirt is a rigid sheath fixedly surrounding the nozzle and having therein the sensor e.g. in a toroidal or annular form, with inward or downward facing perforations to allow entry/exit of vapour, and optionally outward facing perforations to allow exit of vapour. The weighted part of the collapsible skirt may be attached to one or more rigid elements extending axially and internally, or especially externally, of the sheath to the rigid sheath, wherein it may operate mechanically an activator for the sensor e.g. generator or flap or window opener, or may be used to aid removal of vapour; in this latter approach the element may close over the outward facing perforations when the skirt is non collapsed (to help protect the sensor from the environment) but may be moved axially relative to the perforations so a slot or hole in the element may register with the perforations, thereby allowing exit of vapours.
Many forms of detector or analyzer device can be used to determine the total concentration of vapours and optionally their nature(s); the detectors or analyzers can usually detect amounts of more than 0.1 ppm preferably more than 1 ppm of the vapours. Among suitable detectors are spectroscopic and gas chromatographic devices, and olfactory sensors (also called xe2x80x9celectronic nosesxe2x80x9d). The device may be at the site of the pipe or tank etc, though for safety purposes the device may be separate from its detector or sampling head and joined thereto by an analysis line, either for the sample (i.e. for taking a sample of the vapours from the site) or for the signal (e.g. down an optical fibre line). The device can be activated, ready for use, by a prior action of the user, in particular the removal of the nozzle from its location in a fuel pump stand in a filling station, so that the removal will release a depressed arm starting the pump, as well as activate the device e.g. apply power thereto or warm it (if required), or open an optical shutter in a spectroscopic detector. The detector or analyzer device may be battery powered, the battery(ies) being recharged by induction on return of the nozzle and thus detector to the xe2x80x9cpumpxe2x80x9d receiving location when waiting for use, or the device or battery may be attached to one or more solar cells e.g. mounted on the dispenser upper surface.
The detector or analyzer device when comprised by the dispenser may be primed ready for use by prior action of the user on the dispenser. This action may be by depression of a button on an exterior surface of the dispenser such as on its top or head portion or by depression of a spring loaded annular arm surrounding the nozzle and hinged to the distant side of the nozzle or by depression of a spring loaded arm provided with 2 leg portions extending on either side of the nozzle which are hinged to opposing sides of the nozzle, the depression resulting from contact with the tank fuel opening or by movement of the handle of the dispenser, against the urging means, depression or movement causing closure of a battery circuit for the device or generating a priming current for the device. In the case of the handle, the initial movement against the urging means may prime the device, which analyzes the vapour, passes a signal to the processor and hence to the controller and valve. With fast acting detectors the delay between depression of the handle and flow of fuel (assuming a xe2x80x9ccorrectxe2x80x9d fuel) would be negligible. Use of such a priming system could increase the lifetime of any battery or reduce its size or even avoid need for its use.
The dispenser may also comprise means for activating the sensor, which may be an elongate member e.g. arm which is moveable between a rest position when the dispenser is separate from a tank, and a closed position when the nozzle is inserted into a fuel tank and the dispenser urged into contact with the surround to the neck of the tank; the act of urging moves the activating means to the closed position. The activation means may operate a generator to power the sensor and/or processor/controller or charge a battery therefor, or may mechanically operate means to bring vapour and the sensor in contact, preferably by moving vapour to a stationary sensor, e.g. operating a piston to suck vapour past a sensor, or opening a cover over a sensor (either directly or indirectly) allowing vapour to contact the sensor, or moving a sensor into contact with the vapour. Thus an activation lever e.g. a depressable arm can be connected mechanically via levers pivotally to move a piston in a tube, the tube upstream of the piston being air and downstream of the piston being the vapour to be tested, and the piston is moved past a recess or side arm to the tube, in which recess or arm a sensor is located. As the arm is depressed, the levers move the piston which sucks vapour behind it and when the piston moves past the recess or side arm, the vapour is drawn in contact with the sensor. When the nozzle is removed from the tank the depressable arm returns to its rest position moving the piston and hence withdrawing the vapour from the sensor and the tube, thereby purging it to reduce contamination when the nozzle is used again.
The piston may also on its return move vapour out of the tube, e.g. when the tube has a one way entry valve to stop egress of vapour but allow entry and also separately a one way exit valve to allow exit of vapour but deny entry; by this means too the sensor zone may be purged of vapour.
The activation lever may also mechanically move a flap or uncover a window thereby revealing the sensor to the vapour; the window may be in a slatted component adapted to move with respect to its frame between a closed piston covering the sensor and an open position uncovering the sensor. The frame itself may comprise slats, but with one or more of the holes in the slats revealing the sensor.
If desired the activator lever can be part of or an extension of the manually operated activator for the main dispenser valve. In this case squeezing the activator also moves the piston drawing vapour into contact with the sensor; the main dispenser valve in this arrangement is adapted not be moved until after the piston has been moved, the vapour registered by the sensor, and its nature accepted.
Among the possible spectroscopic techniques are infra red (both mid and near IR), ultraviolet and fluorescence spectroscopy and nuclear magnetic resonance (NMR) included pulsed NMR. In each case the vapour passes into or through an open or closed sample cell, and a beam of the appropriate radiation is passed through it and all or part of the spectrum is taken optionally with the aid of refracting or reflecting means e.g. a mirror(s) or prism(s) to multiply increase the path length and arrange the source next to the detector. The IR technique can use a single diode detector or a single multi diode detector, optionally with a filter selective to allow only certain wavelengths through it from the sample onto the detector; the selective filter is particularly important with NIR/FTIR detectors. For distinguishing between aviation gasoline (avgas) and jet fuel AVTUR or AVCAT, IR absorptions at 5000-4800, 4000-4500 (or 4000-4400), 2850-2980, 1130-80, 970-1040 and 680-780 (700-800) cmxe2x88x921 may be used, in both cases the Avgas giving the higher absorptions. Absorptions due to isopentane may specifically be sought to distinguish between Avgas which contains significant amounts of isopentane and jet fuel which does not. In the case of UV fluorescence spectroscopy, radiation at a specific wavelength or wavelengths, e.g. 254, 313, 366, 546 nm may be used to excite fluorescence in the visible region, which is detected. Filters at e.g. 370, 420, 450 and/or 550 nm may also be used.
For use with micro-gas chromatography, the vapours can contact the micro-gas chromatography solid state sensor, e.g. a spiral column etched on a silica/glass wafer, which separates them, and then by means of a suitable detector e.g. an optical diode or polymer coated electrochemical detector e.g. polymer coated Group VIII metal such as Pt, determine the amounts of each component and an indication of its nature. The signals from the latter can be analyzed to determine the total amounts and, if on the xe2x80x9ccorrectxe2x80x9d side with respect to the threshold or otherwise within the tolerances, then the processor can instruct the controller to open the valve allowing flow to occur when required.
The detector can also be a solid state gas sensor, which is a device whose conductivity is changed in the presence of a gas. Further details of such sensors are described in Sensors and Actuators B Vol.8 1992 pp 1-11 by H V Schurmer et al the content of which is herein included by reference. The detector comprises a sensor for the vapour which may be gas permeable, a support e.g. a membrane therefor, a pair of electrodes on either side of the sensor, e.g. having a reference and sensing electrode, means for providing a voltage across the electrodes and means for detecting any change in the conductance of the sensor e.g. a voltmeter or ammeter. The device is used in association with a data processor to process the output from the sensor. The changes may be in the sensor itself or in a device in contact with the sensor (a pellister approach), such as in relation to a ion sensitive/selective layer on an electrically conducting-wire or plate or quartz oscillator with a layer of organic sensor adsorbed thereon; swelling of the polymer causes changes in the oscillation frequency of the quartz oscillator, as in a quartz microbalance. Alternatively the quartz layer in the microbalance may be sensitive to the vapour or may be provided with an optionally organic coated metal layer sensitive to the vapour. Thus the quartz layer may have a coating of Group VIII or IB metal such as copper, nickel, gold or ruthenium, platinum, palladium or rhodium. The metal layer may have had an organic coating e.g. of an organic sulphur compound such as an aliphatic aromatic or araliphatic polar compound e.g. thiol such as one with 4-24 carbons such as 6-16 carbons, e.g. dodecylmercaptan, especially on gold, or an aliphatic N-heterocyclic polar compound e.g. imidazoline with 6-24 carbons in the aliphatic e.g. alkyl or alkenyl group such as oleyl imidazoline. The polar organic treated metal may be more sensitive to one fuel over another e.g. kerosene over avgas, while the untreated metal may have a reverse sensitivity. There may be one sensor per device, or an array of sensors e.g. 2-50, 20-40, 2-20 or 3-6 each sensitive to a different compound, thereby enable a xe2x80x9cfingerprintxe2x80x9d of the vapour to be obtained. While each sensor, or array, may have an associated processor and controller, if desired there may be a number of sensors, but only one processor and controller, the signals from the sensors being scanned and passed to the processor and controller e.g. via a multiplexer. There may be at least one processor per controller usually 1-3, preferably 1, except when a processor is present to provide compensation e.g. for temperature differences between an analysis zone and a standard or another analysis zone.
Solid state sensors e.g. polymer coated metal oxide sensors are commercially available and vary from ones with only one sensor, sold for analysis of and sensitive to gaseous 1-4 carbon alkanes, carbon monoxide or oxygen, or multimatrix ones with many different heads, each sensitive to a different material. It has been found that polymer coated metal oxide sensors sensitive to carbon monoxide and/or methane are sensitive to Avgas and jet fuel as well.
The sensor itself may be inorganic or organic, examples of the former being metal oxide semi conductors, metal oxides SFETS and electrochemical cells, and examples of the latter being conducting polymers, lipid coated wires and Acoustic Wave sensors e.g. operating at 50-500 MHz e.g. 200-300 MHz. Metal oxide semi conductors are usually based on zinc, tin or titanium oxides with a catalytic metal or rare earth metal associated with them e.g. impregnated thereon, for example platinum or palladium gates. Examples are zinc oxide single crystals with suitable metal; these are also known as Taguchi gas sensors. These work by interaction of the hydrocarbon vapour with air over the catalyst to cause changes in the semi conductivity of the oxide; this interaction happens when the catalyst is heated e.g. to 300-400xc2x0 C. by a thin film heater, which is adjacent the sensor, usually on the side distant from the vapour source. By using different catalyst metals and/or different temperatures, different sensors interact with different hydrocarbons to different extents. The act of removal of the fuel nozzle from its stand, which usually starts the fuel pump, can trigger heating the heater or powering the sensor. The metal oxide can be on a support e.g. an oxidized silicon wafer or on porous alumina. These metal oxide gas sensors are preferred for sensing the more volatile hydrocarbons e.g. gasoline over diesel and aviation gasoline over jet fuel.
The conductive polymers may be for example optionally substituted poly pyrroles with a variety of cations e.g. sodium, potassium or lithium, and optionally with pendant functional groups. The hydrocarbon vapours may cause the conductive polymer to swell and/or change its permeability to hydrocarbon vapours and/or interact with the conductive polymer to different extents e.g. with formation of ion pairs thereby changing the conductivity of the polymer e.g. polypyrrole to different extents. The polymers may be used as such as the sensor but are preferably supported on a porous support e.g. alumina, or on a membrane, in which case the membrane itself is also externally protected except for a small area for direct exposure to the vapours.
The output signal from the sensor may be a single one for comparison as explained, with the baseline or threshold or another measured signal. The signals from an array may be used to produce a pattern and then the analysed by chemometric techniques for comparison with known patterns e.g. for gasoline or diesel and a decision on the similarity to the known pattern used to control the valve movement. Preferably a single sensor is used to give information so control is based simply on the total vapour concentration especially when the device is for filling tanks with a more volatile fuel e.g. avgas and stopping filling with a less volatile fuel e.g. kerosene. When the sensor is used to differentiate between vapours of 2 different materials, preferably at least two are used, one or more of higher sensitivity to one material and the other or others being of higher sensitivity to the other material. Sensing of one material being the xe2x80x9ccorrectxe2x80x9d one, would then require a positive signal from one sensor to which it is more sensitive and a negative signal from the less sensitive sensor. This arrangement significantly increases the safety margin for the device. Another way to increase the margin is to have a reserve sensor in place in case of problems with the main one.